INFANEM the driving notion clone

[BetterOffShred]

I can do these very quick on my stripboard build. Will try and get back to you. Are you saying to omit the diode and cap and just a 2.2M in it's place?

[BetterOffShred]

first I want to thank you for the work you did in finding the problem. this helps me out a lot and it trickles down to help everyone who is having problems. second, I want to apologize to anyone who purchased a PCB. these mistakes can happen but I feel that it is my responsibility to warranty and provide some kind of remedy. today this remedy is documenting what might help solve the problem. in the long term, I will do more research based on the photos and the product sample to determine if there was a 47K resistor that was not included in the clone or alternatively if there was a resistor 4M7 that was accidentally marked 470K. I also think that 18v makes the perfect sound into a moving target. many things can go wrong if they are biased by a single resistor vs a resistor divider. it is possible to bias to V+ on only 9v or only 18v but not both simultaneously. the resistor divider increases something called stability. that is a technical term not a guitar player slang. the diode + cap from collector to base depends on a loud signal to decrease the impedance of the cap so that it biases the transistor. that can't happen if there is a problem on the previous stage. for now I can posit these 3 suggestions but it will take some time for me to build it and verify if these are random ideas or an actual working fix to the known problem.

DRIVINGNOTIONproblemsmall.gif

Hey it's no problem at all! I like building and troubleshooting so I'll do my part if I can!

Ok so I added the 47k from base to ground on Q6, and that immediately made the sustain longer. I bypassed the diode and 100n with a 2.2M at Q7 but that didn't matter much. I busted out the probe and pulled the 2nd 5089, and now there is good smooth non sputtery sustain after the 7.5n and at the collector of Q6. So Q7 seems to the problem here.

I'd like to step back for a second and say once again this is a stripboard build, and I have verified it (with my own eyes you know how that goes) with the schematic on separate days to make sure I'm not getting punchy. All this being said it's still a possibility that my build has some issues that the PCB does not, which is why I was hoping someone had built the PCB. Perhaps I should snag a PCB. I can provide pics of my build and the layout etc. (Dirtbox fx)

So back to Q7.. I do not possess the knowledge to know how the 470k and 220k are biasing it, I will breadboard just that transistor and see how it sounds.

[eatyourguitar]

I think the bass fuzz stage is some kind of asymmetrical distortion. distortion stages don't need to be perfectly biased. they are distortion for a reason. but if you have problems you can follow the basic rule 470K pulled up and 47K pulled down. the 2M is completely optional. if you want to fix the problem with biasing, you can replace R24 220K with a 47K. that will totally fix the bias but it will still be a bass fuzz circuit because of the diode there. the 2M gives you some negative feedback even when the diode is out of phase. it bleeds in some stability to what is basically a half wave rectifier. so again 2M won't help you but replacing the 220K pull down with 47K pulldown will definitely fix it. I wonder if this was actually 4M7 and 220K. that would be another working combination to bias that transistor. you can also delete the 470K and leave the 2M from collector to base but that is getting into the more experimental more distorted ways to bias the transistor so you may want to try the first suggestion first before you try the wild experimentation for interesting distortion stages.

[ibarakishi]

we are coming up on the 1 year mark of this thread/project in another little over a month. Whats the verdict on things?

[eatyourguitar]

I am going to make the changes that were discussed here. I need to drill another enclosure. I am still in school so I can only work on this on Mondays and Wednesdays. There was a whole month where I was banned from my mothers house so I definitely lost some time there. I understand your position as well. I really wish BetterOffShred would tell me if the fix worked or not. I think I understand the problem so I will go ahead and do my own fix tomorrow but I still need to drill the box and wire everything. It may take me a week to do it at the rate things are going.

[eatyourguitar]

I also ran out of these jacks. other than that the build is going smoothly.

I just noticed I need to order these special jacks so that it fits. I can use switchcraft 112ax I have in stock but you don't want those because they won't last. that was the same problem why the original INFANEM pedal was breaking all the time. I want to build it better so that it never breaks. the NRJ6HM is the best you can get. the threads are metal. the nuts are metal. the leafs don't get destroyed under normal use.

[ibarakishi]

its fine, i can wait. just wanted to get a solid idea of where things are at across the board.

[mcatano]

Hiiieeeee, just checking in to see if there was a verified build of the PCB yet?

[eatyourguitar]

this is the best I can do right now. I am still working on swapping these parts out in my build. notice you must add the 47K resistor and connect to one of the many ground pads on the PCB. it may not look pretty but it will get the job done. the 470K must be changed to 4M7. I had to order parts for my build so you won't hear from me tomorrow. you can probably use this information as I believe it is correct this time. hopefully that is all the bugs worked out %100. I did not want to make the official announcement until I have tried this myself.

[selfctrl]

Thanks so much for all your hard work on this everyone! Been wanting to build some clones of this for a while. Picked one up from eBay for cheap years ago. I use it all the time, but really wanted a spare (or two). Looking forward seeing it verified.

[BetterOffShred]

I did these mods to my build and something still doesn't sound right. The decay is farty and rumbles as it fades out. Once again my build is a strip based off the schematic not the actual PCB, so there could be some problem there, though I have gone over it many times.

I can try any other ideas fairly quickly. I had to take a break from this build after looking it so hard for so many days

[BetterOffShred]

Speaking of order of magnitude is it possible the bias for Q7 was 470k/22k?

[eatyourguitar]

Speaking of order of magnitude is it possible the bias for Q7 was 470k/22k?

you could do that I guess. it should in theory have the same voltage but it also changes the current bias a little bit. when you have 4M7 you are basically choking off the current to the base. if the goal is to make a clone then you really want to go with 4M7 + 220K. if you were to bias with 4K7 + 220R you would have problems with extremely low gain. everything is on a spectrum from clone to broken. you are more likely to saturate the transistor early if you use 470K 22K. gated farty sounds are consistent with being out of bias but it should not be farty after a 10nF ac coupling cap. it should be a nice distorted square wave gated or not gated. the farts must be from the low side. I suggest doing all the testing on 9v not 18v. use an audio probe to pickup the signal at the collector of Q6. then try again at the collector of Q7. let me know how that goes. make sure your probe has a capacitor in the signal chain to block DC. I want to know if it is fixed with the new values I posted at 9v. This is how I plan to mod the one I have here. Thanks for your help. If you don't mind waiting, you can hang back till I finish testing it. Or you can try it out. Either way, let me know more about how you probed it.

[BetterOffShred]

I have been using 9v. I'll probe it again in the morning

[mcatano]

Hiiieeeee, just checking in to see if there was a verified build of the PCB yet?

^^??